A 1/4”-thick plywood template guided the travel of a router bit that cut through the inner face of this structural insulated panel. Wiring and an electrical box will go into the fall after scooping out the white foam. (Steve Maxwell photo)

Wiring in SIPs panel

Q: How do you install plumbing and wiring in structural insulated panels? I’ve read your articles on this method of building over the years and I’m curious about this point.

A: Structural insulated panels (SIPs) are large, factory-bonded building panels that take the place of stud walls and frame roofs in residential and light commercial projects. They’re made of oriented strand board glued to both faces of rigid foam insulation, and this leaves some people wondering. In fact, your question about plumbing and wiring is the most common one I’m asked about SIPs.

The best approach is to cut vertical grooves into the interior face of the panels, then lay wires and pipes into these grooves, upwards or downwards from the adjacent floor or ceiling frame. After these are installed, fill the grooves with expanding foam then trim the foam with the wall after it’s hard using a hacksaw blade out of its frame. Drywall goes right over top. This approach works very well.

A router following a plywood template is the fastest, neatest way to make multiple wire grooves quickly and neatly. Just remember that all wires and pipes need to be set back at least 1 1/2” from interior wall surfaces. SIPs panels are amazingly strong and this strength isn’t affected by vertical grooves. That said, never create horizontal grooves in SIPs. It reduces panel strength dramatically.

Sewage safeguards

Q: How can I stop sewage from backing up in my basement? Every so often I hear of basements that are ruined when very wet weather causes problems. How can I protect myself ahead of time.

A: You’re wise to ask, since catastrophic basement flooding can often be completely avoided through the use of simple hardware that prevents the back flow of sewage up through floor drains. Trouble of this sort can happen when flooding occurs outside your home, but also as a result of something as simple as a blockage of the pipe between your home and the sewer line.

Hardware is available that allows only the outward flow of sewage, and different designs are on the market. The floating floor drain plug is one. Another type is called a back water valve. I’ve checked with my local hardware store, and these items are both available across Canada. Contact a specialty plumbing retailer if you can’t find a big box hardware store clerk who knows what you’re talking about.

Sealing paver bricks

This roller includes many slits that hold sealing liquid better than conventional rollers. Sealing brick pavers doesn't make them last longer, but does help reduce staining. (Steve Maxwell photo)

Q: Do I really need to seal my new interlocking brick pathway before winter sets in? A friend told me I should apply sealer right away.

A: I’ve never found it necessary to seal brick-paved surfaces, at least not for structural reasons. The masonry used is completely impervious to damage from ice and water. That said, sealers do enhance the appearance of paving bricks, making it less likely they’ll get stained by oil drips from cars. Sealing provides a richer look that retains more colour than bare pavers over the years, too. You’ll get the best results if you use a foam application roller that has slits in it. This feature holds more sealant that a regular roller, while providing very smooth application.

Just remember that once you start sealing, you’re committed to keeping it up to maintain an even appearance. If oil has already dripped on your paving bricks, I find that dish-washing liquid is one way to get rid of the marks. Saturate the stain with the soap, let it sit there for an hour or two, then scrub the area with a plastic-bristle brush and lots of flowing water.